This work will involve investigations into the role which the sodium pump may play in the cellular action of insulin. The principal approach will involve studies on intact muscle cells from both normal and diabetic animals. Some studies will be performed upon the (Na ion plus K ion) - ATPase isolated from the same tissues. The first objective will be to investigate the mechanism whereby insulin increases the intracellular pH, pHi, of muscle and to determine if the action of insulin upon the sodium pump plays any role in this action. A second objective will be to determine if the stimulation of glycolysis by insulin is secondary to the stimulation of the sodium pump by insulin and to determine if this effect is mediated by changes in intracellular pHi, ATP, ADP, or Pi. A third objective will be to see if insulin increases the number of sodium pump sites and/or if the affinity of these pumps for ouabain is changed. A fourth objective will be to determine if the diabetic state in experimental animals is associated with evidence of decreased sodium pump activity and with a decrease in pHi. The experiments will be conducted on frog skeletal muscle (sartorius) and upon rat skeletal muscle (soleus) with the muscle from one leg serving as a paired control for the other. Intracellular pH will be determined by the use of DMO-14C(14C 5,5-dimethyl 1-2,4-oxazolidinedione) as well by pH sensitive glass microelectrodes. Glycolytic rates will be followed by determining lactate with LDH and NAD. 3H-ouabain will be used to determine the number of sodium pump sites and to determine the affinity of these pumps for ouabain. The diabetic state will be investigated using genetically diabetic animals as well as animals made diabetic by injections of alloxan and of streptozotocin.